Video converters have many purposes. One is to convert images from the computer graphic format to a television format. Applications of such transformed images include demonstration tapes, training, animation, design reviews, legal evidence, video transmission and distribution, and presentations.
Commonly, video cameras have been employed to record the computer graphics images from a display screen and provide the desired transformation to television format, which can then be recorded or distributed over a network. However, this technique results in many disadvantages, at least partially resulting from the additional transformation involved. Some of the difficulties include corruption of the chrominance and luminance levels, greater than expected loss of resolution, geometric distortion and no genlock or sync.
Alternatives to the video camera conversion system include hard wired video standards converters. Video signals in one format are applied to the converter input and video signals in the predetermined different format are outputted from the converter to appear on another video display screen. These, too, have disadvantages. Many currently available video standards converters must be disassembled for set-up to accommodate any variations in input parameters. To make such changes in these products, specifications of incoming video signals must be known, the unit dismantled, PROM's, PAL's, and crystals replaced, switches reset, and finally, the unit reassembled. The real problem arises from the fact that within the same category rating, for example, 1000-line graphics, the video signals have slightly different formats due to specification of the clock rates, aspect ratio, vertical and horizontal front and back porches, and sync periods. If the sampling apertures are not set correctly, the image will not be correctly centered or sized when displayed in the new format, such as RS170A.